Marine bioassay acceptability for determining the effects of different emerging contaminants on the marine organism Haliotis midae of South Africa

The presence of emerging contaminants (ECs) in South Africa’s marine coastal waters has received increasing attention, yet their ecotoxicological effects on indigenous species remain poorly understood. A major gap in monitoring is the absence of a standardised marine bioassay protocol. Although South Africa’s National Toxicity Monitoring Programme (NTMP) outlines water quality assessment for inland waters, it excludes marine ecosystems. In contrast, the United States Environmental Protection Agency (USEPA) recommends Haliotis rufescens for Whole Effluent Toxicity (WET) assessments. This study adapts the USEPA WET protocol for South African conditions by employing Haliotis midae, an economically important abalone species native to South Africa. A reference toxicant test with zinc sulphate was conducted, followed by exposures to five ECs commonly detected in South African coastal waters: Acetaminophen, Atrazine, Benzotriazole, Carbamazepine, and Emtricitabine. Toxicity tests at 100 µg/L, 50 µg/L, and 25 µg/L for each EC revealed significant developmental impairments at all concentrations, including the lowest tested. These effects occurred at levels comparable to reported environmental concentrations, underscoring H. midae’s high sensitivity to ECs. The bioassay met all USEPA acceptability criteria, confirming robustness, reproducibility, and environmental relevance. Zinc testing further validated H. midae as a suitable bioassay organism. This standardised, locally relevant assay offers a valuable tool for marine ecotoxicology in South Africa, with potential integration into national monitoring programmes. The work supports United Nations Sustainable Development Goals SDG 6 (Clean Water and Sanitation), SDG 14 (Life below Water), and SDG 15 (Life on Land) by advancing capabilities for monitoring and protecting aquatic ecosystems from emerging pollutants.